Pg:- 104,105 Ch:- 5

• An empirical formula represents the simplest whole-number ratio of elements in a compound.

•  It gives the relative number of atoms of each element but not the exact number of atoms in a molecule.

• The empirical formula of a chemical compound shows the simplest positive integer ratio of atoms present.

• Steps to Determine the Empirical Formula:

  1. Obtain Mass Data: Start with the mass of each element in the compound. This can come from experimental data or from a given problem.

  2. Convert Mass to Moles: Use the atomic masses (from the periodic table) to convert the mass of each element to moles. This is done using the formula:

     Moles of element= Mass of element / atomic mass of element.

  3. Determine the Simplest Ratio: Divide the number of moles of each element by the smallest number of moles calculated. This step normalizes the quantities to the smallest whole numbers.

  4. Adjust to Whole Numbers: If necessary, multiply the resulting ratios by the smallest common factor to convert them to whole numbers.

The empirical formula is the simplest ratio of elements, while the molecular formula gives the actual number of each type of atom in a molecule. For example, the molecular formula of glucose is C₆H₁₂O₆, which can be simplified to the empirical formula CH₂O.